Funny thing I'd just found out in the process of putting this page together... in Pathfinder, size apparently does not impose any limits on grappling. Which I find both hilarious and awesome.
In the Timely System, however, size differences complicate matters. ;)
I forget is Thor not immune to Gamma damage? Also damn all of Hulk's attacks are gamma? Wonder if that means there's a chance when fighting him (if you survive) from contracting permanent radiation damage.
Or perhaps Gamma based super powers? That would be neat, and explain how come lots of Hulk's enemies/acquaintances become/are radiation based (Leader, Red Hulk, Halflife, Gamma Corps, Flux, Harpy, Ravage, etc).
It may be both. My knowledge of Hulk's lore is a bit sketchy, but I think some folks have suffered radiation poisoning from closely interacting with him, and/or super-powers.
Since I can't won't resist, I'll bring up how modern GURPS handles Powers. You can use the same core mechanics for Powers of any kind, be they biological, chi, divine, magical, psychic, spiritual, super, etc. You do this by taking the Advantages (they're kinda like Feats), and applying different Modifiers (Enhancements and Limitations) to them, so the finer points of them work how you need them to work. One such Modifier is simply the... uh... Power Modifier. Yeah, sometimes GURPS has right-to-the-point names for things. XD I won't go into full details, but the short version is, whatever enables a power to work usually has some universal pros and cons; relative to a "wild" (unmodified) version of the trait, if this is a net negative it becomes a Limitation, while a net positive is an Enhancement. Limitations reduce the cost of the trait, Enhancements increase it. "Cosmic" is reserved for Powers that go above and beyond, as is usually an Enhancement.
Hulk would probably have "Super, Gamma" as a Power Modifier, marking it as a subset of the larger "Super" category. Working how you suggest, Corebrute, I'd still call it a net negative. Most "normal" folks who are around you (or even in your "space") too long risk radiation poisoning. The lucky ones who develop powers seem to (at least at first) go a little crazy to very crazy, depending on how many "bad things" come along with the powers. S'like, are you gonna be a She-Hulk or an Abomination, y'know? Also, in GURPS, "You get what you paid for" is the rule of thumb. I think Doc Samson represents that pretty well; Bruce's psychiatrist friend gains powers, but ultimately causes more problems than he solves (at first) for Bruce Banner. Though he later became an ally, the risk of killing your friends or turning them (even temporarily) into super-powered foes, seems like a net negative. Especially as the latter seems plot driven (even if it were reimagined as a TTRPG) and thus almost entirely in the GM's hands.
Author Notes:
In the Timely System, however, size differences complicate matters. ;)